Light emitting diodes (LEDs) are well known solid state light sources. LEDs have many advantages over traditional lighting sources such as incandescent bulbs as they are cheaper to produce, more robust, and require less power. LEDs are especially desirable as they emit light with high power efficiency over specific colors in the spectrum. However, LEDs are not a focused light source and suffer from relatively low light output. The lack of focused light and low light output prevents application of LEDs to uses where high light intensity is desired. Further LEDs cannot be fabricated in different shapes for decorative purposes. Finally, the light output of LEDs cannot be intensified without an optical device to focus the light.
There are many commercial applications requiring high light output. For example, there is a great demand for outdoor and indoor decorative or architectural lighting. Neon lighting is presently used for such applications. Neon or fluorescent lighting uses a glass tube which is filled with neon gas. Such devices may be used for lighting but also for advertising and signs as the tubes may be fabricated into different shapes. Such tubes may have different colors or generate simple white light. The light intensity of a neon tube depends on the color generated.
However neon lighting suffers from a number of problems. Neon lights require a relatively large amount of electricity to offer resulting in greater costs for heavy use such as outdoor signs. Also, neon lights require periodic replacement and maintenance because such lights experience a significant drop off in output after continual use. Further, the maximum length of a neon tube is around seven feet which necessitates more units for large scale uses. All of these factors may create cost issues. Also, neon lights require a high voltage transformer which may create safety issues. Finally, neon lights do not allow for easy change of the light color output.
Another solution for outdoor applications is high intensity discharge (“HID”) lamps. HID lighting technology replaces the filament of the light bulb with a capsule of gas. The light is emitted from an arc discharge between two closely spaced electrodes hermetically sealed inside a small quartz glass tubular envelope capsule. To operate, they require ballasts, which supply proper voltage and control current. The amount of light produced is greater than a standard halogen bulb, while consuming less power, and more closely approximating the color temperature of natural daylight. Unfortunately, HID lighting has a short relative lifetime, requiring periodic replacement. Further, the HID lighting requires greater maintenance and repair.
Thus, there is a need for an LED based device which provides sufficient light intensity for high lighting applications. There is a further need for an LED based device which allows light output to be focused and directed. There is also a need for an LED based device which allows high light output from the end of an optic fiber. There is yet another need form an LED based device which allows bright side light effect. There is also a need for a low power, high reliability, lighting device suitable for commercial applications.